With the development of low temperature poly-silicon (LTPS) touch display panels, the requirements for production processes and designs are getting higher and higher. A process structure of two metal layers is increasingly applied to OLED backplane processes, that is to say, in order to improve pixels of the display panel, a metal layer, which includes a source, a drain, a source line, and a drain line, and a metal layer, which includes a functional layer in a display device, of a TFT array can be realized in a two-layer structure, and insulation is achieved by an insulating layer between the two metal layers. Further, a portion of metals in the two layers are electrically connected through a via hole formed in the insulating layer.
The insulating layer between the two metal layers is generally made of an inorganic layer such as silicon oxide or silicon nitride. The inorganic layer has the disadvantages of poor coverage and bendability, and the like, and is neither suitable for an OLED display device, nor for a flexible display device. The use of an organic material such as polyimide as a material for the insulating layer can overcome the above-described disadvantages of a conventional electrodeless insulating layer. However, a polyimide photoresist used in the conventional insulating layer is a polymer material based on a carbon chain structure, and when a metal layer formed on the insulating layer is required to be patterned, polyimide is easily etched in an oxygen ion etching process, this causes difficulties in the process, and may cause the formation of a recess on the metal layer on the insulating layer, even cause contact of the metal layer with the underlying metal layer, thereby destroying the insulation between the two metal layers, and affecting product quality.
It is to be noted that the above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.